Electric heater.



GEORGE J'. SCHNEIDER, OF DETROIT, MICHIGAN.

ELECTRIC HEATER.

Specification of Letters Patent.

Patented Apr. 16, 1918.

Application led December 31, 1908. Serial No. 470,139.

T0 all whom t may concern:

Be it known that I, GEORGE J. SCHNEIDER, a citizen of the United States of America, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Electric Heaters, of which the following is a specification, reference being had therein to the accompanying drawings.

It is the object of the invention to obtain a metallic sheathed flexible insulated electrical conductor which is peculiarly adapted for use as a heating unit. To this end, the

inventionconsists, first, in the construction, and, second, in the method of manufacturing the same, as hereinafter set forth.

n the drawings- Figure l is a diagrammatic longitudinal section illustrating one method of sheathing the insulated conductor;

Fi 2 is an enlarged cross section through the nished product;

Figs. 3 and 4 are similar views of modified constructions;

Fig. 5 is an elevation of a spiral heating resistance formed in accordance with my invention; l

Fig. 6 is an elevation of another modification;

Fig. 7 is a longitudinal section illustrating the construction of a terminal contact for tions of the conductor so as to avoid the over-heating and burning out at any point. It is-also desirable to distribute the heat by conduction directl from the surface of the resistance, instead7 ofby radiation therefrom. Atthe same time, it is necessary to maintain perfect insulation and for many constructions the conductor must be bent into the desired form after insulation. My improved construction is one which is peculiarly adapted to fulfil these conditions, and consists essentially in a resistance conductor which is first insulated and then covered with a metallic sheathing. Furthermore, the sheathing is contracted about the insulation so as to press the same into firm contactfwith the conductor throughout all portions of the 1atter,.thereby increasing its conductivity to heat and rendering the same uniform, besides offering protection;

The resistance conductor A may be formed from any suitable material and is covered with an insulation B. vFor this purpose, I preferably use some substance, such as asbestos fiber, which is not destroyed or injured by moderate heat. C is the sheath which surrounds the insulation B and is pressed into firm contact therewith.

I preferably apply this sheathing to the insulated conductor by means of a drawing die D, and, as illustrated in Fig. l, a flat strip C of sheet metal is bent around and contracted upon-the insulated conductor by means of this die. The result is that both the metal and the insulating material are compressed and brought into such close contact as to form a good conductor.

If desired, instead of bending` a fiat strip of metal about the insulating conductor, the latter may be placed in a seamless tube and then passed through lthe die to be contracted in diameter and squeezed into contact with the insulating material, such a construction being illustrated in Fi 4. In Fig. 3 a second sheathing C is ent about and contracted upon the sheathing C, the seam being turned preferably to be diametrically opposite the stem of the inner sheathing.

A sheathed conductor, constructed as described, presents a very large superficial area relative to the cross section of the resistance conductor, and on account of the compression of the material the heat is readily conducted from the resistance tothe outer surface. As the sheathing is formed of pliable metal it will not materially diminish the flexibility of the conductor, and consequently any desired form may be given to the strueture. My improved heating unit is designed to be employed as an exposed heating unit, that is-to be used by. itself, and as the resistor, insulation and the sheathing are all formed ofv flexible material, the'unit in its entirety may be readily fashioned. As illustrated in Fig. 5, the sheathed conductor is bent into the form of a helix, which may b used as an immersion coil. Y

As illustrated in Fig. 6, the insulated conductor may be sheathed by a winding G of a metallic wire. This, if tightly wound. about the insulation, will press thesame into firm contact with the resistance conductor, and willform a protecting armor for the insulation, as well as producing an enlarged radiating or conducting surface for distributing the heat. In all of the constructions described, the conductor forms the core or innermost element of the heating unit.

I preferably provide the 'heating resistance with terminal connections by means of which it may be connected directly to the external electric circuit. These terminal connections are preferably formed by a metallic contact which is clamped or otherwise secured to the end of the metallic sheathing, but is insulated therefrom. As illustrated in Fig. 7 H is an insulation surrounding the end portion of the sheathed conductor, and I is the metallic contact .,iece, which is secured4 about the insulation L This contact piece is provided with a reduced shank J, which is electrically connected with the end of the resistance conductor A. With the construction just described, the portion J of the contact may be inserted in a socket or other contact member in the external electric circuit.

Where the heat generated is to be distributed to a largersurface-as for instance, in asad iron, this may be conveniently accomlished by formingthe heat distributing ody, such as K, with channels or grooves L,

in which the sheathed conductor may be laid. f

Such a construction permits of readily replacing the resistance, and at the same time the surrounding body forms a heat storing bod through which the heat is distributed .to t e work surface. v

.nal contact having a What I claim as my invention is:

l. An electrical heating unit, comprising a bendable resistance conductor, a surrounding insulation of refractory bendable material, and a metallic sheathing also bendable surrounding said insulating material and pressing thev latter in firm and heat-conducting contact with the resistance conductor, whereby said heating unit in. its entirety may be bent, said conductor projecting beyond the sheathing insulation, and a termiortion in electrical contact with said projection and another portion secured to but insulated from the metallic sheathing.

2. An exposed fashionable armored and insulated electrical heatin unit, comprising a flexible resistor, a lexi le refractory insulation surroundin the cross-section of said resistor, a flexible metallic sheathing surrounding and contracted upon said insulation to hold all portions thereof in heatconducting contact with said resistor, and a second flexible metallic casing contracted upon the first-mentioned casing and in direc1 firm and heat-conducting contact there- Wit In testimon whereof I aix my signature in presence o two witnesses.

GEORGE J. SCHNEIDER.

Witnesses; NELLE; K rNsELLA, .c HARRY W. GALVIN. 

